Mariner&#39;s compass.



No. 864,171. PATENTED AUG. 27, 1907.

- J. KEAN'.

MARIN'ERS comrAss. APPLIUATIOI TILED AUG. 31, 1905.

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UNITED STATES PATENT OFFICE.

JAMES KEAN, OF GLASGOW, SCOTLAND, ASSIGNOR TO KELVIN AND JAMES WHITE,LIMITED,

' OF GLASGOW, SCOTLAND.

MARINERS COMPASS.

Specification of Letters Patent.

Patented Aug. 27, 1907.

To all whom it may concern:

Be it known that 1', JAMES KEAN, foreman, of Kelvin and James White,Limited, 18 Cambridge street, Glasgow, Scotland, scientific-instrumentmakers, have invented certain new and useful Improvements in theMariners Compass, of which the following is a specification.

This invention which relates to improvements in the mariners compassconsists of a device or appliance for damping down the vibrationscommunicated to a dry compass when disturbed by gun fire or otheragitation.

In order that my invention may be properly understood and readilycarried into effect, I have hereunto appended one sheet of drawings, ofwhich Figure 1 is a vertical section of a compass bowl to which theimprovements embodying my invention are applied. Fig. 2 is a plan of thesame.

The magnetic damper illustrated in the drawings consists of a pair ofmagnets a, b, contained each within a pair of empty thin metal or glasstubes 0, d, constituting a part of a pontoon e and designed to beparallel with the magnets of the compass card not shown. The two tubes0, d, are conveniently coated with a thin layer of rubber f and arebraced together by a bent strip g of German silver which holds themfirmly at a distance of about 5 centimeters from each other. In themiddle of the strip there is fixed at right angles thereto a slightmetal rod or bar of German silver wire 9 about 1 millimeter diameter and2 centimeters long which serves as a center or vertical pole on whichthe magnetic system is free to turn. The weight of the above is soproportioned that it will just float in a mixture of spirit and water.

The spirit and water marked h is contained within the vessel 1', whichvessel is fitted at or near the bottom of the compass bowl 0 and isabout 12 centimeters diameter and 4 centimeters deep. To the cover 2' ofthe vessel i is mounted the socket j for holding the iridium point j forthe compass card in the ordinary way. The pontoon e is placed inside thevessel '6 with its vertical Wire pivot g fitting loosely in conicalshaped holes 70, Z, formed in the bent ends of the guides m, n, theguide marked n is fixed to the floor of the said vessel '5 and the othermarked m being fixed to the roof thereof. The cover 1' is now put on,soldered up, and the mixture of spirit and water h filled in. Thepontoon 6 now floats easily and without friction, and the magnets a, b,with the pontoon follow the compass card into any position it may take.Being in the liquid, the magnetic force of the magnets a, b, tends onlyto exert a slight but requisite drag on the motions of the compass card,making the card less susceptible to irregular disturbances outside, andcausing it to come quickly to rest should it I get large swing ofdeviation away from its proper position.

Claim.

In a dry compass, a closed 1iquid-containing vessel, an upper and alower guide secured within the vessel, a vertical rod loosely mounted insaid guides, and a pair of.

JAMES KEAN.

Witnesses JOHN LInoLn, CATHERINE HAMILTON.

